docs: def pad_timestamp(string, pad_str=PAD_6_UP):
      """
      >>> pad_timestamp('20')
      '209912'
  
      >>> pad_timestamp('2014')
      '201412'
  
      >>> pad_timestamp('20141011')
      '20141011'
  
      >>> pad_timestamp('201410110010')
      '201410110010'
       """
  
      str_len = len(string)
      pad_len = len(pad_str)
  
      if str_len < pad_len:
          string = string + pad_str[str_len:]
  
      return string